Method and implant device for grafting adjacent vertebral bodies

ABSTRACT

A methodology for grafting together adjacent bony structures is provided using an implant device having an endplate with an inner disc portion and outer ring portion spaced from the inner disc portion by a connecting wall disposed therebetween. An endplate interior surface includes a retaining structure for securing the endplate to one of the bony structures, and endplate an exterior surface has an integrally formed socket. A ball-joint rod has a longitudinally extending body and an end, and at least a portion of the ball-joint rod end is curvilinear in shape. The curvilinear ball-joint rod end is rotatably disposed in the endplate socket to fixedly interconnect the bony structures.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/049,487, filed Feb. 22, 2016 (published as U.S. Pat. Pub. No.2016/0166401), which is a divisional of U.S. application Ser. No.13/853,241, filed Mar. 29, 2013 (now U.S. Pat. No. 9,314,347), which isa continuation of U.S. application Ser. No. 13/366,890, filed Feb. 6,2012 (now U.S. Pat. No. 8,245,606), which claims the benefit of andpriority to U.S. Provisional Application No. 61/499,271, filed Jun. 21,2011, which are incorporated herein by reference in their entireties forall purposes.

BACKGROUND

The present disclosure relates generally to a vertebral implant device,and more particularly, to a method and implant device for graftingtogether adjacent vertebral bodies.

Diseases and injury to bone structures, such as the vertebral column,and conditions requiring surgical intervention are relatively common. Avariety of conventional implant or graft devices are presently availablefor use in specific areas. The devices vary in size, shape, materialsused, and insertion techniques. For example, in the vertebral column,grafts may provide restoration, decompression, or stabilization of thespine. Typically these devices include a member that is inserted in thevertebral column to replace an injured portion. An example of such aprocedure is a corpectomy, which involves the replacement of a vertebralbody with an implant or graft. The graft is secured to the adjacentvertebrae via a plurality of fasteners to maintain the position of theimplant in situ.

While these conventional devices may generally provide adequate results,they have several disadvantages. For example, conventional graft devicesutilized in a corpectomy procedure typically have a relatively bulkyall-in-one construction and include several components. Such an implantconstruction limits surgery flexibility, including the approach to thespine. The instrument utilized tor insertion is likewise limited due tothe constraints of existing implant devices.

Thus, there is a need in the art for a graft device that has a modularconstruction such that components can be interconnected when and asneeded to enhance surgery flexibility and offer increased adaptabilityto individual patent anatomy.

SUMMARY

Accordingly, the present disclosure relates to an implant device forgrafting together adjacent bony structures. The implant device has anendplate with an inner disc portion and outer ring portion spaced fromthe inner disc portion by a connecting wall disposed therebetween. Anendplate interior surface includes a retaining structure for securingthe endplate to one of the bony structures, and endplate an exteriorsurface has an integrally formed socket. A ball-joint rod has alongitudinally extending body and an end, and at least a portion of theball-joint rod end is curvilinear in shape. The curvilinear ball-jointrod end is rotatably disposed in the endplate socket to fixedlyinterconnect the bony structures. The methodology includes the steps ofsecuring an endplate to each of the vertebral bodies and interconnectingeach endplate using a ball-joint rod.

One advantage of the present disclosure is that an improved implantdevice is provided that is modular in construction and enhances surgeryflexibility allowing for minimally invasive approaches. Anotheradvantage of the present disclosure is that the implant device is avertebral graft that is easy to assemble and insert from a lateral orlateral extracavity approach. Yet another advantage of the presentdisclosure is that a vertebral implant device is provided thatfacilitates bone grafting. Still another advantage of the presentdisclosure is that the vertebral implant device includes a bristle postto help support bone growth. A further advantage of the presentdisclosure is that the vertebral implant device provides for strong andstable endplate gripping. Yet a further advantage of the presentdisclosure is that the vertebral implant device provides for modular insitu insertion for easier placement. Still a further advantage of thepresent disclosure is that the vertebral implant device provides forlarger endplates which results in less “pistoning” and more aggressivedistraction for enhanced performance. Still yet a further advantage ofthe present disclosure is that the vertebral implant device provides asnap-in ball-joint rod that enables variation in endplate alignment andangulation. Still yet another advantage of the present disclosure isthat the vertebral implant device may include a snap-on bristle cagethat enables generous and stable packing of bone graft. Still anotheradvantage of the present disclosure is that the vertebral implant deviceprovides may include a snap-on allograft strut. Yet another advantage ofthe present disclosure is that the vertebral implant device provides formotion preservation due to a ball-joint construct.

Other features and advantages of the present disclosure will be readilyappreciated, as the same becomes better understood after reading thesubsequent description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vertebral implant device, according toan exemplary Embodiment.

FIG. 2 is a top view of an endplate of the vertebral implant device ofFIG. 1.

FIG. 3 is a side view of the endplate of the vertebral implant device ofFIG. 2.

FIG. 4 is a side view of the endplate of the vertebral implant device ofFIG. 3 including a fastener.

FIG. 5a is an elevational side view of a ball-joint rod of the vertebralimplant device of FIG. 1.

FIG. 5b is an elevational side view of a ball-joint rod having aplurality of spikes, according to another embodiment.

FIG. 6 is a perspective view of a vertebral implant device having abristle post fusion shall member.

FIG. 7 is an enlarged side view of the bristle post fission shaft memberof FIG. 6.

FIG. 8 is a top view of the ball-joint rod and bristle shaft member ofFIG. 6.

FIG. 9 is a perspective view of a vertebral implant device having a ringfusion shaft member.

FIG. 10 is an enlarged side view of the ring fusion shaft member of FIG.9.

FIG. 11 is a top view of the ball-joint rod of FIG. 9.

FIG. 12 is a perspective view of a device for inserting a vertebralimplant into a vertebral region, according to an exemplary embodiment.

FIG. 13 is a flowchart of a method of inserting a vertebral implantdevice into a vertebral region, using the vertebral implant device ofFIG. 1.

FIG. 14 is a side view illustrating a vertebral region having undergonea corpectomy according to the method of FIG. 13.

FIG. 15 is a side view illustrating a pair of endplates inserted betweentwo vertebrae, according to the method of FIG. 13.

FIG. 16 is a side view of the endplates of FIG. 15 illustratingattachment of the endplates to the vertebrae.

FIG. 17 is a side view illustrating attachment of a ball-joint rod tothe endplates.

FIG. 18 is a side view of a bristle fusion shall member attached to theball-joint rod of FIG. 17, according to an exemplary embodiment.

FIG. 19 is a sectional view of the vertebral implant device of FIG. 6secured to two to adjacent vertebral bodies.

FIG. 20 is an elevational view of the vertebral implant device set at apredetermined angle.

DESCRIPTION

Referring to FIG. 1-20, an implant device 10 for use between adjacentbone structures is shown. In this example, the implant device 10 is avertebral implant device 10 designed to be implanted in regions of thespine 12, such as the cervical, thoracic, and lumbar spine, although thelocation of implantation is non-limiting. For example, the vertebralimplant device 10 can be used in the lateral extracavity, anterolateral,or direct anterior regions of the thoracolumbar spine to addressindications relating to trauma, tumors, and degenerative issues such asscoliosis, or the like. The vertebral implant device 10 may serve as amodular mechanical graft to support eventual bone growth. The vertebralimplant device 10 and its individual components can be fabricated fromvarious materials, such as plastic, metal alloys, a bio-absorbablepolymer, or the like, and the selection is non-limiting. The selectedmaterial may be magnetic resonance imaging (MRI) compatible.Implantation of the vertebral implant device 10 may be via lateral orlateral extracavitary approaches, in a manner to be described.

Referring now to FIGS. 2-4, the vertebral implant device 10 of thisexample is illustrated. The vertebral implant device 10 generallyincludes an endplate 14 that provides a direct attachment mechanism tothe adjacent remaining vertebra 10 and distributes forces across thevertebra 16. In this example there is a first endplate 14 and a secondendplate 14 that is spaced apart from the first endplate by a rod 18 orshaft. The endplate 14 may be about 5 mm thick and range from 20-40 mmin diameter. The endplate 14 can be made of various materials, such astitanium, PEEK, a bio-absorbable polymer, or the like. The endplate 14includes an exterior surface 20 and an interior surface 22, and theendplate interior surface 22 is in direct contact with the adjacentvertebral body 16. The endplate interior surface 22 may have a varietyof profiles, such as concentric rings of varying thickness, or the like,to mimic anatomic doming of the vertebrae.

The endplate 14 has a generally circular disc-shaped profile. Theendplate 14 includes an inner disc portion 24 that is spaced apart froma generally planar outer ring portion 26 by a connecting wall 28. Agenerally planar collar 30 extends away from an outer edge of the outerring portion 26.

The endplate inner disc portion 24 is concave to form a socket 32 forreceiving a portion of the ball-joint rod 18 in a manner to bedescribed. The wall of the socket 32 may include apertures 34 so thatbone marrow may pass therethrough from the passageways 36 formed withinthe vertebral implant device 10. Further, the wall of the socket mayinclude another aperture (not shown) for receiving a locking set screwto prevent angular movement of the formed ball-socket joint from a finalposition. In another example, the wall of the socket 32 may include astructural formation, such as circumferentially extending indentations,grooves or the like, to facilitate grasping of corresponding spikes orprotrusions on the ball joint rod end. This would allow gripping of theball joint rod end at various angles but would prevent slipping fromthat predetermined angle, in a manner to be described.

The endplate 14 may also include a retaining structure 40 for securingthe endplate 14 to the adjacent vertebral body 16. Further, the endplate14 may include a plurality of retaining structures 40 that areconcentrically arranged within the endplate interior surface 22 to forman inner ring wall. Additionally, the endplate 12 may include one ormore concentric inner ring walls 42. Each concentric ring well 42 mayhave an increasing diameter to correspond to anatomic endplate surfacesof the adjacent vertebral bodies 16. An example of a retaining Structure40 is a cleat 44 extending outwardly from the endplate interior surface22. Each cleat 44 may have a predetermined shape. In this example, cleat44 has an upper surface that is angled/curved/actuate to conform to ormirror the dome- or bowl-like shape of the upper surface of theendplate. The cleat 44 may be hollow as shown at 45 to form anotherpassageway 36 for bone grail material to travel through, and may connectwith other passageways 36 formed in the endplate interior portion 22.The endplate 12 may also include a plurality of integrally formedapertures 46, and the apertures 46 may assume various shapes, such ascircular or as a notch or the like. The openings formed between theretaining structures 40 similarly form a connection to passageways 36that facilitate the transfer of bone growth therethrough.

Another example of a retaining structure 40 is a spike 48, such as acentral spike as shown at 48 a extending from the center of the endplateinner disc 24 for impactation into an object, such as the adjacentvertebral body 16 or the like. The central spike 48 a can likewise haveapertures 48 b leading to art interior channel 48 c to allow forautograft or bone marrow to seep through and support bone growththerein.

The endplate 12 also includes an opening 34 for receiving a fastener 38,such as a screw or the like, for either tacking or fixedly securing theendplate 14 to the adjacent vertebral body 16 or the like. In anexample, the opening 34 is located in the endplate outer ring 26. If atemporary fixation of the endplate 14 to the anatomic endplate 98 of theadjacent vertebral body is desired, the fastener 38 may be a tack screwhaving a predetermined length, such as 3 mm. Similarly, the fastener 38may be a screw having another predetermined length, such as 10 mm,although other types of fasteners 52 may be utilized.

Referring now to FIG. 5a , a ball-joint rod 18 that interconnects theendplates 14 and provides structural support to the removed vertebralbody 16 is illustrated. The ball-joint rod 18 has a generallycylindrical body portion 54, with a first end 56 and an opposed secondend 56. The ball-joint body portion 54 may vary in length depending onspecific anatomical characteristics. The ball-joint body ends 56 eachhave a semi-spherical shape. Similarly, the ball-joint body end 56 mayhave a spherical shape, or a similar combination. The ball-joint end 56is received in the socket 32 formed in the endplate 14, and thuscorresponds in shape and dimension to mate with the endplate socket 32.For example, the ball-joint rod 18 may be between 5 mm to 30 mm indiameter.

The ball-joint rod 18 may also include other features, such as anintegrally formed groove 58 positioned adjacent the ball joint end andextending circumferentially around the ball-joint body 54. Theball-joint rod groove 58 and the ball-joint body 54 operatively work inconjunction with each other to engage the socket 32 formed in theendplate 14 to create a snap-fit ball-joint 60 to retain the ball-jointrod 18 to the endplate 14. The ball-joint end 56 may be engaged in theend plate socket 32 using a variety of techniques, such as by using aspring loaded ring/washer, set screw, fastener, nitrite ring, or dielike. For example, a locking device (not shown), such as a springwasher, may be inserted in the groove 58 to prevent the ball-joint rod54 from disengaging from the endplate socket 32. The second ball-jointend, a second ball-joint groove and likewise are engaged with the socketformed in the second endplate to also create a snap-fit joint. This typeof universal joint enables each of the endplates 14 to freely moveindependently from each other, as shown in FIG. 20. This flexibilityenables variation in endplate alignment and angulation for improvedinsertion, attachment, and performance of the device 10. The ball-jointrod 14 body 54 can be of various sizes. In this example, the ball-jointbody can range from 5 mm to 30 mm in length. The ball-joint rod body canbe made of various materials, such as, titanium, PEEK, or the like.

The ball-joint rod 18 can also have a variety of other features toenhance performance, such as perforations, a hollow interior/core,extensions, spikes, or the like, to facilitate bone marrow growth andtransit in, through, around passageways formed relative to the device10. For example, the ball-joint end 56 may have apertures 62 connectingwith passageways 36 extending through the endplate for transmitting bonemarrow or graft material 82 therethrough passageways 64 formed in theball-joint rod 18. Likewise, the ball-joint body 54 may have apertures62 to connect with passageways 64.

In another example, an exterior surface of the ball-joint rod body 54can have a plurality of outwardly extending spikes 66, as shown in FIG.5b . The spaces between the spikes 66 may delineate channels 68 for bonegrowth. In an example, the spikes 66 can be arranged on the ball-jointrod end 56, such that the spikes 60 engage corresponding openings 34 inthe endplates 12 to initially lock that ball-joint shaft into theendplate 14 at a selected position or angle 70. The ball-joint rod 18can then be further locked in the selected position or angle byfasteners, such as screws, or the like.

Referring now to FIGS. 6-8 the vertebral implant device 10 may includeanother member removably attached thereto. In an example, the vertebralimplant device 10 includes a fusion shaft member 80 that can be attachedto the ball-joint rod body 54, and that acts as a carrier, support,and/or container for bone grafting tissue, bone growth, or the like.Examples of various potential pathways for bone marrow transit aredepicted in FIG. 19 at 82. The fusion shaft member 80 has acircumferentially shaped body portion 84 that is placed over theball-point shaft body 54. The fusion shaft member body portion 84 mayhave an opening 80 for engaging the ball-joint shaft body 54. The fusionshaft member body 84 also includes a plurality of extension members 88or bristles that further facilitate bone growth and support of thegraft. For example, the bristles 88 may contain a bone growthenhancement material such as allograft and/or autograft. The fusionshaft member 80 can have a variety of dimensions, sizes, shapes, or thelike. In an example, the fusion shaft member 80 is a partial ring havinga C-shape profile and having a circumference of approximately 270degrees and includes a plurality of bristles extending outwardlytherefrom, such as perpendicularly, or the like. The fusion shaft member80 can be clipped in a snap-fit manner onto the ball-joint rod bodyportion. In another example, multiple fission shaft members 80 can bestacked adjacent to one another on the ball-joint rod body 54 foradditional coverage and to help bind the joint. For example, the fusionshaft members 80 may be positioned so that the opening of each isstaggered. The fusion shaft member 80 can be made from a variety ofmaterials, such, as, vicryl, PEEK, or the like. Similarly, the bristles88 may be a microfiber material.

Referring now to FIGS. 9-11, another example of an additional member isillustrated. In this example, the vertebral implant device 10 includes aring member 90, such as an allograft ring or strut, that can be attachedto ball-joint rod body 54 to act as a carrier, support, and/or containerfor bone grafting tissue, bone growth, or the like. The ring member hasan inner surface 92 that is placed adjacent to the ball-joint rod 54 andan outer surface 94 that further facilitates bone growth and support.The ring member 90 can have a variety of dimensions, sizes, shapes, orthe like. In this example, the ring 90 has an opening shown at 96 toform a C-shaped profile, having a circumference of approximately 270degrees and inferior and superior curvatures to span between theendplates. The ring member 90 can be clipped in a snap-fit manner ontothe ball-joint rod body 54. Multiple rings 90 can be placed adjacent toeach other on the bay joint rod body 54, such as for additional coverageor to help bind the joint, or the like. The ring 54 can be made from avariety of materials, such as, vicryl, PEEK or the like.

Referring now to FIG. 12, an insertion device 400 tor implantation ofthe vertebral implant device 10 within the vertebrae 16 of a patient isshown. The insertion device 400 is generally Y-shaped and includes afirst arm 402 having a first gripping portion 402 a and a first handleportion 402 b. The insertion device 400 also includes a second arm 404having a first gripping portion 404 a and a second handle portion 404 b.The first arm and second arm 400, 404 arc pivotably attached at a pivotpoint 406, above which defines the gripping portion and below whichdefines the handle portion. The arms 402, 404 move relative to eachother in scissor-like fashion above the pivot point 406. The first armand second arm gripping portion 408 operatively grips the vertebralimplant device 10. The gripping portion 408 of the insertion device 400includes a ball-joint 410 to mimic the ball-join shaft, while insertingthe device 10. The insertion device 400 also includes a central guidemember 412 for aligning and installing a fastener, such as a lock screwor the like. In operation, when the insertion device 400 is opened, theendplates 12 toggle on the insertion guide.

Referring now to FIG. 13, a flowchart outlining a method of implanting avertebral implant device 10, such as in a corpectomy procedure, isillustrated. The methodology demonstrates the potential for hollowedcomponents which would facilitate bone marrow or other bone matrixtransit. The methodology begins in block 500 with the step of preparingthe site for the graft. For example, a partial or complete corpectomyinvolving the removal of a vertebral body 16 or a portion of a vertebralbody is performed on a patient. One or more vertebral bodies 16 may beremoved, as shown in FIG. 14.

The method advances to block 510, which includes the step of insertingan endplate 14 onto an anatomic 98 endplate of an adjacent vertebralbody 16. The size of the endplate 14 may be preselected using a gauge,such as an endplate sizer. Relevant dimensions include the diameter andlength of the endplate 14. In this example, the insertion guide 400 isutilized to position the endplate 12 on the respective anatomic endplate98. The first endplate and an opposed second endplate are positioned asshown in FIG. 15. The concentric inner rings 42 of the endplate 14assist in the retention of the endplate 14 on the anatomic endplate 98.The retaining members, such as the centrally located spike 48 allows theendplate ring well 42 to be impacted into the anatomical endplate.Similarly, the cleats may also assist in temporarily tacking theendplate 12 in the desired position. As described, the interior portionof the endplate fits over the anatomic endplate 98, such as the cranialand caudal rings. A tack screw may be utilized to hold the endplatefirmly against the vertebral body.

The method proceeds to block 520 which includes the step of securing thefirst endplate and the second endplate to an adjacent vertebral body, asshown in FIG. 16. In this step, pilot holes can be drilled using theguide portion 412 of the insertion device 400 and screws placed thereinwhile the insertion device 400 is holding the endplates 14 fixedly inposition.

The method then proceeds to block 530 which includes the step ofmeasuring the distance between the endplates, such as using a caliper.An appropriately sized ball joint rod 18 is selected and using theinsertion device 100, the spherical ends 56 of the selected ball-jointrod 18 are disposed within the socket 32 formed in each endplate 14, asshown in FIG. 17. In this step, the ball-joint rod is snapped inposition white the insertion device is over-distracting the endplates.The socket joint is open on one side to all the ball joints tofacilitate snapping in place. The ball-joint rod 18 may be secured tothe endplate 14. For example, a collar or groove portion 88 of thespherical end of the ball-joint rod may engage the socket 82 to form theball and socket joint 60. The collar may be threaded to secure in place,or a lock screw, as previously described, may be utilized. The lockingset screw may be utilized to keep the ball socket joint 60 from pivotingon implantation, until alignment is complete. If a ball-joint rod suchas that described in FIG. 5b is utilized, that the relative angularposition of the anatomical vertebral body with respect to the ball-jointrod may be set as shown in FIG. 20, such as by snap-fitting the bristleends into a corresponding aperture in the socket. Advantageously, apositive fit is achieved and the snap-in fit makes assembly easier.

If it is desired to preserve the functionality of the joint, then themethodology ends. The ball and socket arrangement of the graft allowsfor relative movement of the adjacent vertebrae. If functionality of thejoint is to be limited, the method proceeds to block 540 which includesthe step of selecting and attaching a second member to the ball-jointrod. In an example, the mobility of the joint is limited using a lockingscrew as a cam to lock the angular position between the graft and anupper or lower vertebral body, such as between 15-20 degrees ofangulation or the like. Further each endplate can be set at a differentangle. In another example, a fusion member 80 such as a bristle postmember and/or an allograft strut may be located onto the ball-joint rodbody 54, as shown in FIG. 18. The bristle post member 80 may be snap fitonto the ball-joint rod body 54. These secondary devices promote bonegrowth around the graft, so that the adjacent vertebral bodies are fusedtogether.

The method can be modified, in various manners, such as by adding steps,removing steps, rearranging steps, or the like. For example, theendplates may be further customized by heating the endplate and moldingaround the anatomical endplate to improve the bond therebetween.Advantageously, the device 10 may be assembly in situ and is readilycustomizable.

The present disclosure has been described in an illustrative manner. Itis to be understood that the terminology which has been used is intendedto be in the nature of words of description rather than of limitation.Many modifications and variations of the present disclosure are possiblein light of the above teachings. Therefore, within the scope of theappended claim, the present disclosure may be practiced other than asspecifically described.

What is claimed is:
 1. An implant device for grafting together adjacentbony structures of a body, said implant device comprising: a firstendplate configured to be fixed to a first vertebral body; a secondendplate configured to be fixed to a second vertebral body; a ball jointrod having a longitudinally extending body and a first end and a secondend, wherein at least a portion of the ball joint rod first end iscurvilinear in shape and at least a portion of the ball joint rod secondend is curvilinear in shape, and the curvilinear ball joint rod firstend and the curvilinear ball joint rod second end are rotatably disposedbetween the first endplate and the second endplate; a fusion shaftmember disposed on the ball joint rod body; and a plurality of bristlesextending outwardly from the fusion shaft member.
 2. The implant deviceof claim 1, wherein the first and second endplates each include acollar.
 3. The implant device of claim 1, wherein the first and secondendplates include a passageway for transporting bone materialtherethrough.
 4. The implant device of claim 1, wherein the firstendplate comprises an endplate retaining structure that is a centrallylocated spike protruding from an interior surface of the first endplate.5. The implant device of claim 1, wherein the endplate retainingstructure is an inner ring wall protruding from an interior surface ofthe first endplate.
 6. The implant device of claim 1, further comprisinga fastener extending through an aperture in the first endplate into thefirst vertebral body for securing the first endplate to the firstvertebral body.
 7. The implant device of claim 1, wherein a portion ofthe ball joint rod is semi-spherical in shape.
 8. The implant device ofclaim 1, wherein a portion of the ball joint rod is spherical in shape.9. The implant device of claim 1, wherein each end of the ball joint rodincludes a curvilinear ball joint rod end that is rotatably disposedbetween the first endplate and the second endplate to fixedlyinterconnect the first vertebral body and the second vertebral body. 10.The implant device of claim 1, wherein the first endplate is fixed at apredetermined angle with respect to the ball joint rod at a joint formedbetween the first endplate and the ball joint rod.
 11. The implantdevice of claim 1, wherein the ball joint rod includes a plurality ofoutwardly projecting members.
 12. The implant device of claim 11 whereinthe first endplate includes a plurality of apertures and each ball jointrod projecting member is disposed in a corresponding ball joint rodaperture.
 13. The implant device of claim 1, wherein the ball joint rodincludes a passageway for transporting bone material therethrough. 14.The implant device of claim 1, wherein the ball joint rod body includesa groove, and a retaining member is disposed in the groove to retain aball joint rod end in a first endplate socket.
 15. The implant device ofclaim 1, wherein the first vertebral body and the second vertebral bodyare adjacent vertebral bodies.
 16. An implant device for graftingtogether adjacent bony structures of a body comprising: an endplatehaving a retaining structure for securing the endplate to one of thebony structures; a ball joint rod having a ball-joint rod end, whereinat least a portion of the ball-joint rod end is curvilinear in shape,and the curvilinear end portion is disposed in a portion of the endplateto fixedly interconnect the bony structures; and a fusion shaft memberpartially surrounding the ball-joint rod, and the fusion shaft memberincludes a plurality of bristles extending outwardly from the fusionshaft member.
 17. The implant device of claim 1, wherein the endplateincludes a collar.
 18. The implant device of claim 1, wherein theendplate includes a passageway for transporting bone materialtherethrough.
 19. The implant device of claim 1, wherein the endplateretaining structure is a centrally located spike protruding from aninterior surface of the endplate.
 20. The implant device of claim 1,wherein the endplate retaining structure is an inner ring wallprotruding from an interior surface of the first endplate.